Oddly amusing (5)
I believe the answer is:
droll
'oddly amusing' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for droll that I've seen before include "Comic" , "Mildly amusing" , "Drily amusing" , "Oddly amusing or comical" , "Whimsical - amusing" .)